In various networking contexts, it is often necessary to send messages from one node to a designated subset of other connected nodes. Two methods of messaging commonly used are point-to-point (a.k.a. unicast) and broadcast.
Point-to-point messaging assumes every node is addressable via a unique identifier and the sender node addresses and sends a copy of a message to each designated receiver node. It is the most common method of delivering messages in Internet Protocol (IP) networks. Point-to-point messaging is expensive in terms of resources when the number of designated receivers is large since a given message may be duplicated and sent over many different paths.
Broadcast messaging involves sending a single message simultaneously to all receivers. Examples are over-the-air (broadcast) television and cable and satellite content delivery. In broadcast messaging, there is not a built-in mechanism for limiting a message to a subset of designated receivers.